IUD may carry higher risk for breast cancer in certain women

By Val Willingham, CNN

Updated 1516 GMT (2216 HKT) July 9, 2014

Birth control methods12 photos

A woman's choice – Women have many choices when it comes to avoiding pregnancy. According to the Centers for Disease Control and Prevention, 99% of sexually active women from 2006 to 2010 used at least one contraceptive method at some point. Here's a look at a variety of birth control methods and how they each work.

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Birth control methods12 photos

IUD – An intrauterine device, or IUD, is a T-shaped flexible device that's inserted by a doctor into a woman's uterus. The devices blocks sperm and changes the lining of the uterus, which may keep a fertilized egg from attaching. Pregnancy is prevented from three to 12 years, depending on the type.

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Birth control methods12 photos

The pill – Approved in 1960 by the U.S. Food and Drug Administration, oral contraceptives involve taking a daily pill with a combination of estrogen and a progestin. The hormones prevent ovulation and thicken a woman's cervical mucus, blocking sperm from fertilizing an egg.

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Birth control methods12 photos

Female condom – Condoms aren't just for men. The female condom fits inside the vagina with a ring at one end that covers the cervix. When used correctly all of the time, the National Institutes of Health says that it's 95% effective, with the bonus protection from sexually transmitted infections.

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Birth control methods12 photos

Diaphragm – The diaphragm also fits inside the vagina, but only covers the cervix, where it blocks sperm from entering the uterus. It is made of silicone and can last up to two years. A spermicide must be used for greatest effectiveness.

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Birth control methods12 photos

Cervical cap – The cervical cap is similar to a diaphragm, only smaller in size and made out of rubber instead of silicone. It is useful for women who find it hard to keep a diaphragm in place.

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Birth control methods12 photos

Implant – Implants are flexible, matchstick-size devices that are surgically inserted into a woman's arm. They slowly release the hormone progestin into the body, which prevents a woman's ovaries from releasing eggs. The protection lasts up to several years.

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Birth control methods12 photos

The patch – For women who don't want to take a pill or insert a device, the Ortho Evra birth control patch sticks to the body and releases pregnancy-preventing hormones through the skin. A woman must change her patch once a week, for three weeks in a row. No patch is used in the fourth week, then the cycle starts again.

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Birth control methods12 photos

Vaginal ring – NuvaRing, approved for use in the United States in 2001, is a small, flexible ring inserted into the vagina. It releases estrogen and progestin, the same pregnancy-preventing hormones found in most variations of the birth-control pill.

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Birth control methods12 photos

Vaginal sponge – Introduced in 1983, the Today Sponge was pulled from the market after fears of toxic shock but returned in 2005 following design changes. The sponge contains spermicide and can be inserted into the vagina before sex, like a diaphragm, to prevent pregnancy.

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The shot – Depo-Provera, an injection form of birth control, provides protection for three months with hormones that prevent ovulation and block sperm. It doesn't contain estrogen as do some other forms of birth control. As a result, it is a popular option for women who can't take estrogen or who are breastfeeding.

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Morning-after pill – Emergency contraception, frequently referred to as the morning-after pill, can be taken to prevent pregnancy up to five days after unprotected sex. It can prevent the ovaries from releasing eggs and thickens a woman's cervical mucus. The morning-after pill can also thin uterus lining, which could prevent a fertilized egg from attaching.

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Story highlights

Study of Finnish women using progesterone-releasing IUD found higher instance of breast cancer

The women were using the IUD to help with their heavy periods

Two earlier studies did not show such a risk

Modern contraceptives have radically changed women's lives, but they are not risk free.

A new study out of the journal of Obstetrics and Gynecology finds the levonorgestrel-releasing intrauterine system (LNG-IUS) or progesterone-releasing IUD, may be associated with a higher than expected incidence of breast cancer.

This form of IUD was originally developed as a contraceptive, but later was also used as a treatment for women who suffer from heavy periods (menorrhagia) as well as endometriosis and chronic pelvic pain.

Levonorgestrel is a synthetic progesterone, which is a hormone that's naturally produced in a woman's body. It regulates ovulation. The hormone causes changes to the uterine lining and mucus in the cervix which makes it harder for sperm to reach the uterus, therefore making it more difficult to conceive. Because it strengthens the uterine lining, it helps cut down on heavy bleeding.

Levonorgestrel is also the hormone used in the Plan B contraceptive, better known as the morning after pill.

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In this study, Finnish researchers from the Department of Obstetrics and Gynecology at the Hyvinkää Hospital in Hyvinkää, Finland, wanted to examine the association between premenopausal use of the LNG-IUS and cancer rates, especially when it came to endometrial adenocarcinoma (cancer of the uterine wall).

The study followed more than 93,000 Finnish women between the ages of 30 and 49. All of the subjects were using the hormone-releasing IUD to treat their heavy periods from 1994 to 2007. At that time, up to 60% of all LNG-IUSs sold in Finland were used for heavy periods and not for contraception.

Investigators found that over time, the device did not significantly raise the risk of uterine cancer or ovarian, pancreatic and lung cancers. But researchers did see a spike in the number of breast cancer cases, especially in women between the ages of 45-49, compared to women in the general population who were not using this particular IUD.

"The number of diagnosed new breast cancer cases among Finnish women who used LNG-IUS for menorrhagia was 19% higher than in Finnish general population," said Dr. Tuuli Soini, the lead author of the study.

However, the research does not say that this type of IUD causes breast cancer. Soini also adds "one limitation of our study was that women suffering from heavy menstruation may in fact represent a selected group of women who may have other risk factors for cancer, such as factors related to lifestyle, genetic factors, just to name a few."

According to Soini, this study is the first linking premenopausal LNG-IUS use and breast cancer.

Two earlier studies did not reveal an increased cancer risk, according to the study.

For physicians, this research is a new piece of information they can pass on to those patients.

"It's a great reminder that we need to weigh the benefits of some of these methods against the risks," said Dr. Angela Marshall, director of Comprehensive Women's Health in Silver Spring, Maryland. "We need to educate our patients, because many of these therapies may work, but some could have serious side effects. Women need to be told. Then it's up to the patient, along with a doctor's guidance, to make the decision."

The study authors agree.

"LNG-IUS use seemed to protect against endometrial cancer, which is a common cancer type steadily increasing in the population," said Soini. "We are still convinced LNG-IUS is the best treatment modality for heavy menstrual bleeding, a common health problem affecting the quality of life of a large proportion of female population overall. We certainly hesitate to recommend any change of the clinical menorrhagia management guidelines."

Soini also stressed, "However, health benefits and health risks should be carefully taken into account while counseling menorrhagia patients, in relation to any hormonal or surgical therapy."